Effects of Hg and Ga on microstructures and electrochemical corrosion behaviors of Mg anode alloys

The effects of Hg and Ga on the electrochemical corrosion behaviors of the Mg-2%Hg, Mg-2%Ga and Mg-2%Hg-2%Ga (mass fraction) alloys were investigated by measurements of polarization curves, galvanostatic tests and measurements of electrochemical impedance spectroscopy. Scanning electron microscopy, X-ray diffractometry and energy dispersive spectrometry were employed to characterize the microstructures and the corroded surface of the above alloys. The results demonstrate that the microstructure of the Mg-2%Ga alloy is solid solution and the Mg-2%Hg and Mg-2%Hg-2%Ga alloys have white second-phases at the grain boundaries. The Mg-2%Ga alloy has the worst electrochemical activity and the best corrosion resistance, showing a mean potential of -1.48 V and a corrosion current density of 0.15 mA/cm2. The Mg-2%Hg-2%Ga alloy has the best electrochemical activity and the worst corrosion resistance, showing a mean potential of -1.848 V and a corrosion current density of 2.136 mA/cm2. The activation mechanism of the Mg-Hg-Ga alloy is dissolution-deposition of the Hg and Ga atoms.

Effectiveness Evaluation Study of Self-made Zinc Alloy Sacrificial Anode under Chloride Salt Erosion Environment

To investigate the effectiveness of self-made zinc alloy sacrificial anode material for the protection of reinforcement in concrete under chlorine salt erosion environment,salt solution immersion corrosion and electromigration accelerated corrosion tests were used to evaluate the effectiveness of self-made zinc alloy anode with the help of relevant cathodic protection guidelines and evaluation criteria for the corrosion of reinforcement in concrete.The results showed that the protection was effective because the potential of the zinc alloy anode protection steel bar in the salt solution satis?ed the“-780 mV(SCE)”validity criterion.The self-corrosion potential(E_(corr))of the sacri?cial anode protection steel in concrete was greater than-276 mV,and the protective current density of the zinc alloy anode was 1-3μA·cm^(-2),which met the standards of EN12696-2000,further indicating that the self-made zinc alloy sacri?cial anode had a good protection combining with the polarization resistance and the appearance of the corroded surface of the steel in concrete.The microscopic morphology of the corroded surface and the composition of the corrosion products indicates that the mortar of the self-made zinc alloy anode has a lower pH than the imported anodes,so the long-term protection of the selfmade zinc alloy sacri?cial anode needs to be further improved.

Lithiophilic Li-Si alloy-solid electrolyte interface enabled by high-concentration dual salt-reinforced quasi-solid-state electrolyte

Solid polymer electrolytes(SPEs)are urgently required to achieve practical solid-state lithium metal batteries(LMBs)and lithium-ion batteries(LIBs),Herein,we proposed a mechanism for modulating interfacial conduction and anode interfaces in high-concentration SPEs by LiDFBOP.Optimized electrolyte exhibits superior ionic conductivity and remarkable interface compatibility with salt-rich clusters:(1)polymer-plastic crystal electrolyte(P-PCE,TPU-SN matrix)dissociates ion pairs to facilitate Li+transport in the electrolyte and regulates Li^(+)diffusion in the SEI.The crosslinking structure of the matrix compensates for the loss of mechanical strength at high-salt concentrations;(2)dual-anion TFSI^(-)_(n)-DFBOP^(-)_(m)in the Li^(+)solvation sheath facilitates facile Li^(+)desolvation and formation of salt-rich clusters and is conducive to the formation of Li conductive segments of TPU-SN matrix;(3)theoretical calculations indicate that the decomposition products of LiDFBOP form SEI with lower binding energy with LiF in the SN system,thereby enhancing the interfacial electrochemical redox kinetics of SPE and creating a solid interface SEI layer rich in LiF.As a result,the optimized electrolyte exhibits an excellent ionic conductivity of9.31×10^(-4)S cm^(-1)at 30℃and a broadened electrochemical stability up to 4.73 V.The designed electrolyte effectively prevents the formation of Li dendrites in Li symmetric cells for over 6500 h at0.1 mA cm^(-2).The specific Li-Si alloy-solid state half-cell capacity shows 711.6 mAh g^(-1)after 60 cycles at 0.3 A g^(-1).Excellent rate performance and cycling stability are achieved for these solid-state batteries with Li-Si alloy anodes and NCM 811 cathodes.NCM 811‖Prelithiated silicon-based anode solid-state cell delivers a discharge capacity of 195.55 mAh g^(-1)and a capacity retention of 97.8%after 120 cycles.NCM 811‖Li solid-state cell also delivers capacity retention of 84.2%after 450 cycles.

Surface‑Alloyed Nanoporous Zinc as Reversible and Stable Anodes for High‑Performance Aqueous Zinc‑Ion Battery

Metallic zinc(Zn)is one of the most attractive multivalent-metal anode materials in post-lithium batteries because of its high abundance,low cost and high theoretical capacity.However,it usually suffers from large voltage polarization,low Coulombic efficiency and high propensity for dendritic failure during Zn stripping/plating,hindering the practical application in aqueous rechargeable zinc-metal batteries(AR-ZMBs).Here we demonstrate that anionic surfactant-assisted in situ surface alloying of Cu and Zn remarkably improves Zn reversibility of 3D nanoporous Zn electrodes for potential use as high-performance AR-ZMB anode materials.As a result of the zincophilic ZnxCuy alloy shell guiding uniform Zn deposition with a zero nucleation overpotential and facilitating Zn stripping via the ZnxCuy/Zn galvanic couples,the self-supported nanoporous ZnxCuy/Zn electrodes exhibit superior dendrite-free Zn stripping/plating behaviors in ambient aqueous electrolyte,with ultralow polarizations under current densities up to 50 mA cm^(‒2),exceptional stability for 1900 h and high Zn utilization.This enables AR-ZMB full cells constructed with nanoporous ZnxCuy/Zn anode and K_(z)MnO_(2)cathode to achieve specific energy of as high as~430 Wh kg^(‒1)with~99.8%Coulombic efficiency,and retain~86%after long-term cycles for>700 h.

Effect of rolling processing on microstructure and electrochemical properties of high active aluminum alloy anode

The effect of rolling processing on the microstructure,electrochemical property and anti-corrosion property of Al-Mg-Sn-Bi-Ga-In alloy anode in alkaline solution(80℃,Na2SnO3+5 mol/L NaOH)was analyzed by the chronopotentiometry (E-T curves),hydrogen collection tests and modern microstructure analysis.The results show that when the rolling temperature is 370℃,the electrochemical activity of Al anode decreases gradually with the increase of pass deformation in rolling,while the anti-corrosion property is improved in the beginning and then declined rapidly.When the pass deformation of rolling is 40%,the Al anode has good electrochemical activity as good as the anti-corrosion property and with the increase of rolling temperature,both electrochemical activity and anti-corrosion property of Al anode increase first and then decrease.When the rolling temperature is 420 ℃,the aluminum alloy anode has the most negative electrode potential of about-1.521 V(vs Hg/HgO)and the lowest hydrogen evolution rate of 0.171 6 mL/(min·cm2).The optimum comprehensive performance of Al alloy anode is obtained.

Microstructure and battery performance of Mg-Zn-Sn alloys as anodes for magnesium-air battery

Four Mg-x Zn-y Sn(x=2,4 and y=1,3 wt.%)alloys are investigated as anode materials for magnesium-air(Mg-air)battery.The self-corrosion and battery discharge behavior of these four Mg-Zn-Sn alloys are analyzed by electrochemical measurements and Mg-air battery tests.The results show that addition of Sn stimulates the electrochemical activity and significantly improves the anodic efficiency and specific capacity of Mg-Zn alloy anodes.Among the four alloy anodes,Mg-2Zn-3Sn(ZT23)shows the best battery discharge performance at low current densities(≤5 m A cm^(-2)),achieving high energy density of 1367 m Wh g^(-1)at 2 mA cm^(-2).After battery discharging,the surface morphology and electrochemical measurement results illustrate that a ZnO and SnO/SnO_(2)mixed film on alloy anode surface decreases self-corrosion and improves anodic efficiency during discharging.The excessive intermetallic phases lead to the failure of passivation films,acting as micro-cathodes to accelerate self-corrosion.

Effect of rolling technologies on the properties of Pb?0.06wt%Ca?1.2wt%Sn alloy anodes during copper electrowinning

The objective of this work was to study the effect of different rolling technologies on the properties of Pb-0.06wt%Ca-1.2wt%Sn anodes during copper electrowinning and to determine the relationship between the properties of the anodes and rolling techniques during copper electrowinning. The anode process was investigated via anodic polarization curves, cyclic voltammetry curves, electrochemical impedance spectra, and corrosion tests. The microscopic morphology and phase composition of the anodic oxide layers were observed by scanning electron microscopy and X-ray diffraction, respectively. Observable variations in the electrocatalytic activity and reaction kinetics of anodes during electrowinning indicated that the electrochemical behavior of the anodes was strongly affected by the rolling technology. An increase in the rolling number tended to decrease the oxygen evolution overpotential and the corrosion rate of the anodes. These trends are contrary to that of the apparent exchange current density. Furthermore, the intensities of diffraction peaks associated with PbO, PbOx, and α-PbO2 tended to increase with increasing rolling number. In addition, the rolled anodes exhibited a more uniform microstructure. Compared with one-way rolled anodes, the eight-time cross rolled anodes exhibited better electrocatalytic activity and improved corrosion resistance.

Passivation of Insoluble Anode from Ti－base Alloys in Preparation of Electrolytic MnO＿2

The passivation behavior of insoluble anode from 8 kinds of Ti-base alloys in the 40% H_2SO_4(aq)and1 mol/L MnSO_4 -0.75 mol/L H_2SO_4 was studied respectively by analyzing potential-controlling stationarypolarization curve. Results indicate that the passivation curves of Ti-base alloy insoluble anode are analogousto that of pare titanium anodc in spite of the critical passivation current density i_b for the former is somewhathigher and passivation retaining current density i_p increases significantly, the passivation region diminishes.the passivation becomes not so clear. Ou the basis of electrochemical and X-ray diffraction data the passivationmechanism of pure titanium anode in EMD industry is discussed and authors suggest that the Ti- base alloyanode is better than the pure titanium anode.

Effects of Al and Sn on electrochemical properties of Mg-6%Al-1%Sn (mass fraction) magnesium alloy as anode in 3.5%NaCl solution

Mg-6%Al-1%Sn(mass fraction) alloy is a newly developed anode material for seawater activated batteries. The electrochemical properties of Mg-1%Sn, Mg-6%Al and Mg-6%Al-1%Sn alloys are measured by galvanostatic and potentiodynamic tests. Scanning electron microscopy(SEM) with energy dispersive spectrometry(EDS) is used to characterize the microstructures of the experimental alloys. The results show that the Mg-6%Al-1%Sn alloy obtains more negative discharge potential(-1.38 V(vs SCE)) in hot-rolled condition. This is attributed to the fine dynamically recrystallized grains during the hot rolling process. After the experimental alloys are annealed at 473 K for 1 h, the discharge potentials of Mg-6%Al-1%Sn alloy are more negative than those of Mg-6%Al alloy under different current densities. After annealing at 673 K, the discharge potentials of Mg-6%Al-1%Sn alloy become more positive than those of Mg-6%Al alloy. Such phenomenon is due to the coarse grains and the second phase Mg2 Sn. The discharge potentials of Mg-1%Sn shift positively obviously in the discharge process compared with Mg-6%Al-1%Sn alloy. This is due to the corrosion products pasting on the discharge surface, which leads to anode polarization.

EIS studies the effect of Zinc to Al-Zn alloy used for cathodic protection in 3% NaCl solution

Electrochemical impendence spectroscopy （EIS） is applied to investigate the dissolution behavior of Al-Zn alloys in 3% NaCl solution at different polarization potentials. A new reaction model is proposed, and the activation mechanism of zinc in Al-Zn alloys is achieved. There are three intermediates in the dissolution process： Znad^＋, Znad^2＋ and Alad^＋, ,of which only Zni can activate Al-Zn alloys. Most Znnd^＋ is produced by β-phase,and the alloys with 2. 3% - 3. 8% （wt） Zn dissolve rapidly. The Al-Zn alloys of heart-shaped EIS are active in 3% NaCl solution, thus EIS characteristic can be used to distinguish the activa-tion of Al-Zn alloys.

Self-healing Ga-based liquid metal/alloy anodes for rechargeable batteries

With the rapid development of electronics,electric vehicles,and grid energy storage stations,higher requirements have been put forward for advanced secondary batteries.Liquid metal/alloy electrodes have been considered as a promising development direction to achieve excellent electrochemical performance in metal-ion batteries,due to their specific advantages including the excellent electrode kinetics and self-healing ability against microstructural electrode damage.For conventional liquid batteries,high temperatures are needed to keep electrode liquid and ensure the high conductivity of molten salt electrolytes,which also brings the corrosion and safety issues.Ga-based metal/alloys,which can be operated at or near room temperature,are potential candidates to circumvent the above problems.In this review,the properties and advantages of Ga-based metal/alloys are summarized.Then,Ga-based liquid metal/alloys as anodes in various metal-ion batteries are reviewed in terms of their self-healing ability,battery configurations,working mechanisms,and so on.Furthermore,some views on the future development of Ga-based electrodes in batteries are provided.

Influence of aluminium and lead on activation of magnesium as anode

Mg-6%Al, Mg-5%Pb and Mg-6%Al-5%Pb （mass fraction） alloys were prepared by induction melting with the protection of argon atmosphere. Their electrochemical activations in different electrolyte solutions were investigated by galvanostatic test. The microstructures of these alloys and their corroded surfaces were studied by scanning electron microscopy, X-ray diffractometry and emission spectrum analysis. The results show that the activation of magnesium is not prominent when only aluminum or lead exists in the magnesium matrix, but the coexistence of the two elements can increase the activation. The activation mechanism of Mg-Al-Pb alloy is dissolving-reprecipitating and there is a synergistic effect between aluminium and lead： the precipitated lead oxides on the surface of the alloy can facilitate the precipitation of Al（OH）3, which can peel the Mg（OH）2 film in the form of 2Mg（OH）2AI（OH）3 and activate the magnesium matrix.

Study on the Rare Earth Sealing Procedure of the Porous Film of Anodized 2024 Aluminum Alloy

The rare earth sealing procedure of the porous film of anodized aluminum alloy 2024 was studied with the fieldemission scanning electron microscope (SEM) and X-ray energy dispersive spectroscopy (EDS). The results show thatRE solution can form cerium oxide/hydroxides precipitation in the pores of the anodized coating at the beginning ofsealing. At the same time, the spherical deposits formed on the surface of the anodized coating created a barrierto the precipitation of RE solution in the pores. When the pore-structured anodizing film is covered all with thespherical deposits, RE conversion coating will form on the surface of the anodized coating. The reaction of thecoating formation was investigated by employing cyclic voltammetry. The results indicate that accelerator H2O2 actsas the source of O2 by carrying chemical reaction in course of coating formation. In the mean time, it maybe carrieselectrochemical reaction to generate alkaline condition to accelerate the coating formation. The porous structure ofthe film is beneficial to the precipitation of the cerium hydroxides film.

Microstructure and abrasive wear behaviour of anodizing composite films containing Si C nanoparticles on Ti6Al4V alloy

Anodized composite films containing Si C nanoparticles were synthesized on Ti6Al4 V alloy by anodic oxidation procedure in C4O6H4Na2 electrolyte. Scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and X-ray photoelectron spectroscopy(XPS) were employed to characterize the morphology and composition of the films fabricated in the electrolytes with and without addition of Si C nanoparticles. Results show that Si C particles can be successfully incorporated into the oxide film during the anodizing process and preferentially concentrate within internal cavities and micro-cracks. The ball-on-disk sliding tests indicate that Si C-containing oxide films register much lower wear rate than the oxide films without Si C under dry sliding condition. Si C particles are likely to melt and then are oxidized by frictional heat during sliding tests. Potentiodynamic polarization behavior reveals that the anodized alloy with Si C nanoparticles results in a reduction in passive current density to about 1.54×10-8 A/cm2, which is more than two times lower than that of the Ti O2 film(3.73×10-8 A/cm2). The synthesized composite film has good anti-wear and anti-corrosion properties and the growth mechanism of nanocomposite film is also discussed.

Revealing the structure design of alloyed based electrodes for alkali metal ion batteries with in situ TEM

Alloyed based anode materials with high theoretical specific capacity and low reaction potential are considered to be highly potential high-energy density anode materials for alkali metal ion batteries(AMIBs).Thus,the design of alloyed based materials with high electrochemical performance has attracted great attention.Among the numerous characterization methods for guiding electrode materials design,in situ transmission electron microscopy(TEM)gradually plays an irreplaceable role due to its high temporal and spatial resolution in directly observing the change of morphology,crystal structure and element evolutions.Herein,we reviewed the two current research hotspots and mainly focused on the structure design of alloyed based electrode material under the guidance of in situ TEM.Specifically,various nanostructure designs of alloyed based electrode materials with guidance of in situ TEM were employed to solve the key scientific issues of the violent volume change during alloying/dealloying processes for enhanced electrochemical performances.Mainly through introducing buffer space in the electrode material to reduce volume change to improve structural stability,including porous structure(0 D),nanotube structure(1 D),simple hollow structure,yolk-shell structure and some hybrid hollow structures(3 D).Furthermore,the direct guidance of in situ TEM is expected for creating new opportunities to nextgeneration electrode material design for AMIBs.

Corrosion protection of magnesium alloys anode by cerium-based anodization coating in magnesium-ait battery

CeN_(3)O_(9)·6H_(2)O(0.5,1.0,1.5,and 2.0 g/L)was added into an 8.0%NaCl electrolyte solution to investigate this electrolyte for use in a Mg-air battery.The effects of the amount of CeN_(3)O_(9)-6H_(2)O on the corrosion resistance of an AZ31 Mg alloy anode and battery performance were investigated using microstructure,electrochemical(dynamic potential polarization method and electrochemical impedance spectroscopy),and battery measurements.The re sults show that the addition of CeN_(3)O_(9)·6H_(2)O to the electrolyte leads to the formation of a Ce(OH)_(3)protective film on the surface of the AZ31 Mg alloy that improves the corrosion resistance of the Mg alloy.An increase in the concentration of CeN_(3)O_(9)·6H_(2)O results in a denser Ce(OH)_(3)protective film and decreases corrosion rate of the AZ31 Mg alloy.When the concentration of CeN_(3)O_(9)·6H_(2)O is 1.0 g/L,the corrosion rate of the Mg alloy is the lowest with a corrosion inhibition rate of70.4%.However,the corrosion rate increases due to the dissolution of the Ce(OH)_(3)protective film when the concentration of CeN_(3)O_(9)-6H_(2)O is greater than 1.0 g/L.Immersing the Mg alloy in the electrolyte solution containing CeN_(3)O_(9)-6H_(2)O for 50 h leads to the formation of the Ce(HO)_(3)protective film on its surface,which was confirmed by scanning electron microscopy of the AZ31 alloy.The Mg^(2+)charge transfer resistance increases by 69.5Ωfrom the equivalent circuit diagram,which improves the corrosion resistance of the Mg alloy.The discharge performance of CeN_(3)O_(9)·6H_(2)O improves according to a discharge test,and the discharge time increases by 40 min.

Achieving stable K-storage performance of carbon sphere-confined Sb via electrolyte regulation

Potassium-ion batteries(PIBs)have been considered as one of the most promising alternatives to lithiumion batteries(LIBs)in view of their competitive energy density with significantly reduced product cost.Moreover,alloy-type materials are expected as a high-performance anode of PIBs thanks to their intrinsic chemical stability as well as high theoretical specific capacity.Unfortunately,the serious incompatibility between alloy-type active materials and electrolytes,especially for the formation of unstable solidelectrolyte interfacial(SEI)films,often leads to insufficient cycle life.Herein,the formation mechanism of SEI films in the K-storage systems based on carbon sphere confined Sb anode(Sb@CS)were investigated in commercially available electrolytes.Physical characterizations and theoretical calculation revealed that the solvents in the dilute electrolyte of 0.8 M KPF_(6)/EC+DEC were excessively decomposed on the interface to generate unstable SEI and thus result in inferior K-storage stability.On the contrary,a salt-concentrated electrolyte(3 M KFSI/DME)can generate inorganic-dominated stable SEI due to the preferential decomposition of anions.As a result,the prepared Sb@CS in the matched 3 M KFSI/DME electrolyte delivered a high reversible capacity of 467.8 m A h g^(-1)after 100 cycles at 100 m A g^(-1),with a slow capacity decay of 0.19%per cycle from the 10th to the 100th cycle.These findings are of great significance for revealing the interfacial reaction between electrodes and electrolytes as well as improving the stability of Sb-based anode materials for PIBs.

Seamlessly Merging the Capacity of P into Sb at Same Voltage with Maintained Superior Cycle Stability and Low-temperature Performance for Li-ion Batteries

Among the alloying-type anodes,elemental Sb possesses the suitable yet safe plateau,simple lithiation pathway,small voltage polarization,high conductivity,and superior cycle stability.However,challenge is that its intrinsic capacity is rather low(660 mAh g^(-1)),<1/6 of silicon.Herein,we propose a seamless integration strategy by merging the voltage and capacity of phosphorus and antimony into a solid solution alloy.Interestingly,the enlistment of P is found greatly enlarge the capacity from 660 to 993 mAh g^(-1) for such Sb_(30)P_(30) solid solution,while maintaining a single and stable discharge plateau(~0.79 V)similar to elemental Sb.Various experimental characterizations including XPS,PDF,Raman,and EDS mapping reveal that in such a material the P and Sb atoms have interacted with each other to form a homogenous solid solution alloy,rather than a simple mixing of the two substances.Thus,the Sb_(30)P_(30) exhibits superior rate performances(807 mAh g^(-1) at 5000 mA g^(-1))and cyclability(821 mAh g^(-1) remained after 300 cycles).Furthermore,such Sb_(60-x)P_(x) alloys can even deliver 621 mAh g^(-1) at
30℃,which can be served as the alternative anode materials for high-energy and low-temperature batteries.This unique seamless integration strategy based on solid solution chemistry can be easily leveraged to manipulate the capacity of other electrode materials at similar voltage.

Fabrication and characterization of anodic oxide nanotubes on TiNb alloys

Titanium and its alloys have been extensively used as implant materials owing to their high specific strength, good biocompatibility and excellent corrosion resistance. Oxide nanotubular array layer can be formed on Ti alloy surface by electrochemical anodization treatment. In this work, the morphology of nanotubes formed on Ti-Nb alloys（Nb content of 5 wt%, 10 wt%, 20 wt%, 30 wt% and40 wt%） was investigated using an electrolyte containing ethylene glycol and NH_4 F. Oxide layers consisting of highly ordered nanotubes with a range of diameters（approximately40-55 nm for the inner diameter and 100-120 nm for the outer diameter） and lengths（approximately 10-20 lm） can be formed on alloys in the Ti-x Nb system, independent on the Nb content. The nanotubes formed on the Ti-Nb alloy surface were transformed from the anatase to rutile structure of titanium oxide. The oxide nanotubular surface is highly hydrophilic compared with the intact Ti Nb foil. The surface wettability varies with the nanotube diameter. As the nanotube diameter increases while the nanotube layer thickness remains constant, the capillary wetting of the nanotube surface decreases and the surface becomes less hydrophilic.Annealing changes the nanotubular surface wettability further and establishes less hydrophilic surface conditions due to the removal of hydroxyl groups and residue fluoridecontaining species. It is believed that the surface wettability is changed due to the decreasing content of hydroxyl groups in ambient atmosphere. This work can provide guidelines for improving structural and environmental conditions responsible for changing surface wettability of Ti Nb surfaces for biomedical applications.

Antimony-based intermetallic compounds for lithium-ion and sodium-ion batteries:synthesis,construction and application

The development of alternative electrode materials with high energy densities and power densities for batteries has been actively pursued to satisfy the power demands for electronic devices and hybrid electric vehicles. Recently, antimony（Sb）-based intermetallic compounds have attracted considerable research interests as new candidate anode materials for high-performance lithium-ion batteries（LIBs） and sodium-ion batteries（SIBs） due to their high theoretical capacity and suitable operating voltage. However, these intermetallic systems undergo large volume change during charge and discharge processes, which prohibits them from practical application. The rational construction of advanced anode with unique structures has been proved to be an effective approach to enhance its electrochemical performance. This review highlights the recent progress in improving and understanding the electrochemical performances of various Sb-based intermetallic compound anodes. The developments of synthesis and construction of Sb-based intermetallic compounds are systematically summarized. The electrochemical performances of various Sb-based intermetallic compound anodes are compared in its typical applications（LIBs or SIBs）.